Safeguarding the authenticity of value documents by means of luminescent substances has been known for some time. Preferably, host lattices doped with rare earth metals are used, with the absorption and emission regions being variable within a broad range through suitable coordination of rare earth metal and host lattice. The use of magnetic and electrically conductive materials for safeguarding authenticity is also known. Magnetism, electrical conductivity and luminescence emission are detectable by machine using commercially available measuring instruments, while luminescence with emission in the visible region in sufficient intensity is also detectable visually.
WO 2005/036481 A1 describes an apparatus and a method for checking value documents having luminescent feature substances. Carrying out the evaluation of the captured luminescence radiation on the basis of an integrated luminescence measurement, i.e. integrating the measured luminescence radiation of a track extending across the value document, makes it possible to capture and distinguish weakly luminous feature substances especially easily.
DE 10 2005 033 598 A1 discloses a sheet-shaped value document having luminescent feature substances and the production and check of such a value document. The value document described therein contains a luminescent feature substance which is present both with low concentration over the full area and with higher concentration in certain partial areas.